There has been proposed a variety of structures for connecting links of a watchband. As a structure for adjusting a length of a band, there is generally known a structure wherein a connecting pin having a shape of a hairpin is inserted in holes of adjacent links so as to connect the links.
However, in such a connecting structure, the connecting pin is small so that a special tool is necessary to insert and pull out the pin, or the pin may be lost during the operation for adjusting the band length. Moreover, an accurate cross section shape is required for securely connecting links, and repeated use is not possible. When adjusting, there happens that one pin is difficult to pull out, while another easily falls out because of variances in dimensions of the hole and connecting pin. Hence, the operability at the adjustment of the band length is poor and a skilled operator is needed.
In order to resolve the above-described problems, there is a structure disclosed in Japanese Utility Model Application Laid Open 57-45312. In the structure, a keyway, which is a locking portion, is integrally formed inside a hole of each of the lugs formed on a case. However, it is extremely difficult to machine the keyway. In addition, the machining accuracy cannot be maintained so that mass production is difficult.
Japanese Utility Model Application Laid Open 6-74309 discloses another structure for resolving the above-described problems of the conventional structure. The structure has a stopper ring provided with a keyway thereby forming a locking member.
However, in the above-mentioned conventional band connecting structure, the keyway and a projection of a connecting pin are both very small, rendering it impossible to see them during the operation for inserting the connecting pin and engaging the projection with the keyway. Accordingly, it is difficult to position the keyway and the projection so that the operability is poor. Moreover, the structure is defective, for example, in that, in order to securely engage the connecting pin in the locking member, the connecting pin must be pushed in the axial direction while circumferentially rotating the pin, thereby rendering the operability extremely poor.
An object of the present invention is to provide a structure for connecting links of a band, wherein links or a watchcase and a link of the band can be easily connected and disengaged.